Soputan

Indonesia

1.112°N, 124.737°E; summit elev. 1785 m

All times are local (unless otherwise noted)

BNPB reported that explosions at Soputan were detected at 1300, 1437, and 2008 on 6 February; observers 10 km away saw dense reddish gray ash plumes rising 3 km above the crater. At 0106, 0204, 0311, and 0320 on 7 February Strombolian activity ejected tephra as high as 1 km above the crater. A pyroclastic flow traveled 2 km down the E flank. Thunderous sounds were reported, and dense ash plumes rose 2.5 km and drifted W. Constant tremor was detected. Ashfall was reported in multiple districts including Pasan (5 km SSE), Tombatu (16 km SSW), Belang (17 km SSE), and Ratatotok (20 km S). The Alert Level remained at 4 (on a scale of 1-4); residents and tourists were advised not to approach the craters within a radius of 4 km, or 6.5 km on the WSW flank. [Correction; the Alert Level remained at 3.]

Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano rises to 1784 m and is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.